Post-inflammatory hyperpigmentation is a condition wherein skin darkens or acquires a brown color after experiencing some type of trauma. This can result from the injection of chemicals into the skin, from skin burns, or even in some situations from bruises.
In the treatment of varicose veins or telangiectasis, for example, about three to four weeks after the veins are injected with a sclerosing solution, the purple colors of the veins disappear as the blood vessels dissolve. As these purple lines of the blood vessels are removed, they are replaced by brown lines due to post-inflammatory hyperpigmentation.
Hyperpigmentation can also be a manifestation of hormonal changes as in Addison's disease, pregnancy, or the use of anovulatory pills. Darkening may also result from increased melanogenesis, as is seen in hemochromatosis, or from silver deposits, as are seen in argyria.
It is believed that the characteristic brown discoloration of the skin is due to melanin pigmentation. Melanin is the substance which is formed for example when a caucasian develops a suntan. Thus, it is believed that post-inflammatory hyperpigmentation is a condition where the skin develops sort of a "mini-suntan" in the areas affected by trauma. Also, exposure to sunlight accentuates this pigmentation. Generally, this discoloration is not permanent and will dissipate over a period of time from about 1 to 24 months. Since many patients are treated primarily for cosmetic reasons, this time period for removal of the discoloration is, in most cases, unacceptable.
At present, no successful treatment for prevention or reduction of post-inflammatory hyperpigmentation is known to exist. While various compositions containing agents for bleaching melanin pigment are available, these are generally intended for treating surface layers of skin, such as, for example, treating sunburn. These compositions are somewhat successful for treatment of surface tissue, but are completely ineffective for treating hyperpigmentation of subsurface layers. The present invention, however, resolves this problem by providing compositions and methods for the prevention, elimination, or substantial reduction of post-inflammatory hyperpigmentation.